Police in Ely are investigating a report of an assault on a woman in Plymouth Woods on Monday morning.
A 27-year-old woman was walking around Archer Road Recreation ground at around 10am on the Bank Holiday when she was grabbed and thrown to the floor by an unknown person.
She screamed for help and the individual, believed to be wearing a rain jacket and gloves, ran off.
No further description is available at this time.
It is believed other members of the public were in the area at the time and we would ask these people to please contact us as they might have vital information.
Officers have searched the area and have been doing additional patrols.
The woman is very distressed by this incident and we would appeal for anyone with information to come forward.
Please contact South Wales Police on 101 or Crimestoppers anonymously on 0800 555 111 quoting ref *317825.